2024 Volume 23 Issue 2 Pages 73-79
Kaki-shibu is made from astringent types of persimmon fruit, with none made from non-astringent types. We have produced Kaki-shibu using the PCNA (pollination constant and non-astringent) type of persimmon when fruits have high tannin levels as well as astringent-type fruits. We expected to obtain a new material of Kaki-shibu from PCNA fruits, since PCNA fruits have different chemical properties regarding tannins compared with astringent types. In this study, we focused on how the differences in chemical properties of these kaki-shibu affect their biological activities, such as antioxidation and α-glucosidase inhibition, using each Kaki-shibu made from PCNA ‘Fuyu’, PCA (pollination constant and astringent) ‘Atago’, and PVA (pollination variant and astringent) ‘Hiratanenashi’. The results showed that the total polyphenol content of PCNA ‘Fuyu’ was comparable to that of non-PCNA with no significant difference, when the same weight of freeze-dried samples was prepared from Kaki-shibu and dissolved with the same amount of distilled water. Kaki-shibu from PCNA ‘Fuyu’ showed marked DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity, as well as that from PCA ‘Atago’ and PVA ‘Hiratanenashi’. Furthermore, Kaki-shibu from PCNA ‘Fuyu’ also showed high α-glucosidase inhibitory activity by non-competitive inhibition, the same as Kaki-shibu from astringent types. These results suggest that Kaki-shibu made from PCNA ‘Fuyu’ is also reliable for commercial use instead of Kaki-shibu made from astringent types. However, Kaki-shibu from PCNA ‘Fuyu’ did not show activity as high as Kaki-shibu from astringent types based on an oral glucose tolerance test using an ICR mouse, probably due to the higher sugar contents in Kaki-shibu of PCNA ‘Fuyu’. Further investigation is needed to evaluate their functionality in vivo.
